Abstract: The initial corrosion laws and electrochemical behaviors of 2A12 aluminum alloy were investigated by using alternate immersion test, scanning electron microscopy (SEM) as well as electrochemical impedance spectroscopy (EIS). The results showed that obvious pitting phenomena were observed for all the specimens in various Cl^- containing solutions after 48h alternate immersion. With the increase of Cl^- concentration, the initiation and development of pitting corrosion were promoted and more corrosion products formed. At a lower Cl^- concentration, the corrosion process was mainly controlled by charge transfer resistance; with increasing Cl^- concentration, the electrochemical characteristic transferred to the mixed control of charge transfer resistance and Warburg resistance.